1. Field of the Invention
This invention relates to a sewing machine, more particularly to an improvement in structure for a sewing machine which is designed to effectively sew an edge of a floor mat for an automobile or the like along its varying contour.
2. Description of the Prior Art
A typical conventional sewing machine comprises a mounting table, on which a workpiece such as a floor mat for an automobile (commonly referred to as a "car mat") or the like is mounted, a sewing mechanism adapted to sew an edge of the workpiece mounted on the mounting table, a rotating mechanism adapted to rotate the mounting table, a vertically moving means adapted to vertically move the mounting table, and a horizontally moving mechanism adapted to horizontally move the mounting table.
The sewing machine of this arrangement is disadvantageous in the fact that since it needs programming to control the rotating mechanism, and the vertically and horizontally moving mechanisms to be moved in accordance with each contour of the workpiece to be sewn. This programming was troublesome and consequently decreased the efficiency of sewing operation. In addition, when the workpiece of a different contour is to be sewn, the program must be revised so as to properly control those mechanisms. When the workpiece particularly the car mat of a varying contour with relatively many corners is to be sewn, program had to be revised frequently. This was a serious problem in the sewing machine of this type.
Further, actuators comprising the rotating mechanism described would become large in dimension, since it has to move the mounting table which is generally heavy in weight. Consequently the overall structure of the sewing machine may undesirably become bulky.